Help! Which London hotel?

I've today been advised that a colleague and I will be attending a conference at the Institute of Physics in Portland Place in a few weeks which will require a two night stay. The conference organisers have negotiated special b+b rates at the Holiday Inn Regents Park, The Thistle hotel at Marble Arch and the Radisson Sussex Edwardian (Granville Place).The last Thistle I stayed in a few months ago(Kensington Park)wasn't great which may cloud my objectivity slightly. Anyone any recent experience of any of these please? Also, is there anywhere decent to eat around any of these (our subsistence allowance is paltry)without the loss of one or more of our limbs??
Thanks
DL

[buns]

DL

I have never stayed at any of the hotels on offer - all I would say is that the Radison and the Thistle are some 20 minutes walk away from Portland Place.

There are a number of places just off Oxford Street along the way and St Christopher's Place and surrounding area is full of restaurants and this is only a short walk from either hotel.

Carluccios is another favourite and is just round the corner from Portland Place

buns